Looks like there will be a grace period. Just saw more to the rumor. The FPs will be flagged for 2 days and after two days they will be cancelled.What would make sense is if there was a grace period - i.e. the FPs disappear if there's no reservation attached for 24 hours. But if you rebook and your FPs overlap, then you're OK.
Still won't solve the throwaway campground issue...